 Most of these survived into the post Norman Conquest era and are the core of later Parliamentary Boroughs and municipal corporations.Following the successful reconquest from the Vikings by Alfred's descendants Edward and Æthelstan, the latter made a series of reforms in law, the Codes issued at the Council of Grately, which gave additional impetus to the urban development of the burhs which hitherto had been mainly forts.The burhs drew commerce by every channel; the camp and the palace, the administrative centre, the ecclesiastical centre (for the mother-church of the state was placed in its chief burh), all looked to the market for their maintenance.